Connection between commutative algebra and topology

The main aim of this paper is to show how commutative algebra is connected to topology. We give underlying topological idea of some results on completable unimodular rows.     

Photolysis of zinc azide in the solid state

The photolysis of anhydrous zinc azide prepared by (1) dehydration of Zn(N₃)₂·2H₂O and (2) precipitation by acetone from aqueous solution, under the action of high pressure mercury arc is reported here. The pressure of nitrogen developed during photolysis under steady-state conditions at constant intensity is a linear function of t^1/2 in both the samples. The rate of photolysis is a linear function of intensity at constant temperature. A detailed analysis of the dark rate suggests that the dependence on t^1/2 should be due to the diffusion of nitrogen from the reaction site to the surface of the solid azide. An appropriate mathematical analysis is presented. The linear dependence of the rate of photolysis on the intensity of irradiation is interpreted in terms of the reaction of a trapped exciton with an adjacent azide ion. Absence of any detectable photoconduction in the wavelength range of the irradiating radiation suggests that excitons are the most probable reactive species. The sample of zinc azide obtained by the first method decomposes faster than the other under identical conditions, and has a slightly lower energy of activation of 1.4 kcal/mole compared to 1.75 kcal/mole for the second. These differences are discussed in terms of the defect concentrations of the two azide samples.     

Porous GaN as a template to produce surface-enhanced Raman scattering-active surfaces

Surface-enhanced Raman spectroscopy (SERS) substrates have been prepared by depositing Au or Ag on porous GaN (PGaN). The PGaN used as the template for the metal deposition in these studies was generated by a Pt-assisted electroless etching technique. PGaN was chosen as a potential SERS template due to its nanostructured surface and high surface area, two characteristics that are important for SERS substrates. Metal films were deposited either by solution-based electroless deposition or by thermal vacuum evaporation. SERS spectra were recorded at lambda = 752.5 nm for Au films and at lambda = 514.5 nm for Ag films deposited on PGaN. The SERS signal strength across the metal coated PGaN substrates was uniform and was not plagued by "hot" or "cold" spots on the surface, a common problem with other SERS surfaces. The Ag film deposited by electroless deposition had the highest overall SERS response, with an enhancement factor (EF) relative to normal Raman spectroscopy of 10(8). A portion of the increase in EF relative to typical SERS-active substrates can be assigned to the large surface area characteristic of the PGaN-Ag structures, but some of the enhancement is intrinsic and is likely related to the specific morphology of the metal-nanopore composite structure.     

Recalculation of monomer reactivity considering the effect of monomer partitioning in microemulsion

From the copolymerisation data for the microemulsion polymerisation of both partially water soluble monomers ethylacrylate (EA)-methylmethacrylate (MMA) the concentration of the monomer at the polymerisation loci was calculated. While the reported copolymerisation data for the microemulsion copolymerisation of styrene (Sty)-methylacrylate (MA), monomer pair with different solubility and polarity and Sty-butylacrylate (BA), monomer pair with similar solubility and different polarity was used to calculate the monomer concentration at loci. It was inferred from the non-constancy of f^′_A/f_A and f^′_B/f_B ratio that the preferential site of polymerisation might be the emulsifier layer in case of Sty-MA and Sty-BA. While, based on the monomer fraction in the copolymer and the constancy of f^′_A/f_A and f^′_B/f_B it was concluded that microemulsion polymerisation for monomer pair EA-MMA, having similar solubility and polarity, conforms more to bulk polymerisation, where there is no preferential site of polymerisation. The loci concentration rather than feed value was used to recalculate the reactivity at the site of polymerisation. Also the loci concentration was calculated assuming their sum at the polymerisation site equal to unity.     

Phase‐Stable CsPbI3 Nanocrystals: The Reaction Temperature Matters

High temperature colloidal synthesis for obtaining thermal, colloidal and phase‐stable CsPbI₃ nanocrystals with near‐unity quantum yield is reported. While standard perovskite synthesis reactions were carried out at 160 °C (below 200 °C), increase of another ≈100 °C enabled the alkylammonium ions to passivate the surface firmly and prevented the nanocrystals from phase transformation. This did not require any inert atmosphere storage, use of heteroatoms, specially designed ligands, or the ice cooling protocol. Either at high temperature in reaction flask or in the crude mixture or purified dispersed solution; these nanocrystals were observed stable and retained the original emission. Different spectroscopic analyses were carried out and details of the surface binding of alkyl ammonium ligands in place of surface Cs in the crystal lattice were investigated. As CsPbI₃ is one of the most demanding optical materials, bringing stability by proper surface functionalization without use of secondary additives would indeed help in wide spreading of their applications.     

N-(acridin-9-yl)arenesulfonamides: Synthesis,quantum chemical studies and crystal structure analysis to establish the tautomeric preferences

The potentiality of the N-(acridin-9-yl)arenesulfonamide moiety as a hybrid pharmacophore due to the distinct pharmacological activities of acridines and aryl/heteroaryl sulfonamides prompts to synthesise N-(acridin-9-yl)arenesulfonamides and study their structural properties. Various N-(acridin-9-yl)arene/heteroarenesulfonamides were obtained through the development of a new methodology adopting the Pd₂(dba)₃-catalyzed CN bond formation strategy for the reaction of 9-chloloroacridine with arene/heteroarenesulfonamides. The 1H and ¹³C NMR spectra suggest these N-(acridin-9-yl)arene/heteroarenesulfonamides to exist solely as the sulfonimide tautomer rather than anticipated sulfonamide form and was confirmed by the single crystal XRD analysis of one of the newly synthesized compounds. The quantum chemical studies rationalized this tautomeric preference revealing that the sulfonimide tautomers are more stable than the sulfonamide tautomers by ?0.67 to ?5.12?kcal/mol in the gas phase. In the solid state, the sulfonimide tautomer is stabilized by intermolecular hydrogen bond between NH?OS and π? π stacking between the acridine rings.     

Design,synthesis and therapeutic potential of 3-(2-(1<Emphasis Type="Italic">H</Emphasis>-benzo[<Emphasis Type="Italic">d</Emphasis>]imidazol-2-ylthio)acetamido)-<Emphasis Type="Italic">N</Emphasis>-(substituted phenyl)benzamide analogues

Background

The emergence of bacterial resistance is a major public health problem. It is essential to develop and synthesize new therapeutic agents with better activity. The mode of actions of certain newly developed antimicrobial agents, however, exhibited very limited effect in treating life threatening systemic infections. Therefore, the advancement of multi-potent and efficient antimicrobial agents is crucial to overcome the increased multi-drug resistance of bacteria and fungi. Cancer, which remains as one of the primary causes of deaths and is commonly treated by chemotherapeutic agents, is also in need of novel and efficacious agents to treat resistant cases. As such, a sequence of novel substituted benzamides was designed, synthesized and evaluated for their antimicrobial and anticancer activities.

Methodology

All synthesized compounds were characterized by IR, NMR, Mass and elemental analysis followed by in vitro antimicrobial studies against Gram-positive (Staphylococcus aureus), Gram-negative (Salmonella typhi and Klebsiella pneumoniae) bacterial and fungal (Candida albicans and Aspergillus niger) strains by the tube dilution method. The in vitro anticancer evaluation was carried out against the human colorectal carcinoma cell line (HCT116), using the Sulforhodamine B assay.

Results, discussion and conclusion

Compound W6 (MIC_{sa, st, kp}?=?5.19 µM) emerged as a significant antibacterial agent against all tested bacterial strains i.e. Gram-positive (S. aureus), Gram-negative (S. typhi, K. pneumoniae) while compound W1 (MIC_{ca, an}?=?5.08 µM) was most potent against fungal strains (A. niger and C. albicans) and comparable to fluconazole (MIC?=?8.16 µM). The anticancer screening demonstrated that compound W17 (IC₅₀?=?4.12 µM) was most potent amongst the synthesized  compounds and also more potent than the standard drug 5-FU (IC₅₀?=?7.69 µM).

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